1. Field of the Invention
The invention relates to a suspended grid ceiling having panels in grid openings, and particularly to such ceilings where there is a special need to hold the panels down in place on the flanges of the beams forming the grid openings.
2. The Prior Art
Suspended ceilings used extensively in building construction have a grid of intersecting beams suspended by wires from a structural ceiling. The grid has rectangular openings formed by the intersecting beams, that receive laid in panels. Such a ceiling is shown in U.S. Pat. No. 4,827,681, for instance, incorporated herein by reference.
The beams are formed of a web of flat steel roll formed into an inverted T. The panels are supported on the flanges of the T, with the hanging wires anchored above in the structural ceiling, and connected below to holes in the web of the beam.
Generally, in suspended ceilings, the weight of a panel is enough to bias the panel downward and keep it in place in the grid opening.
There are many suspended ceiling installations, however, where it is desirable or necessary to hold a panel in place within a grid opening by retaining members, such as clips. For instance, in suspended ceilings in gymnasiums and and other large open areas, the ceiling is subjected to gusts of air or wind that may blow the panels out of place if retaining members are not used. Retaining members are also desirable, for instance, in suspended ceilings used in clean rooms, or other contained environments. Such a ceiling is shown in copending U.S. patent application Ser. No. 10/346,039, filed Jan. 16, 2003, for CEILING GRID WITH SEAL, incorporated herein by reference. In such ceilings, retaining members, such as hold down clips, keep the panels in close contact with the seals that exist between the panels and the grids, to avoid air movement through the ceiling.
Retaining members, such as hold down clips, are particularly necessary in a suspended ceiling in areas prone to seismic events, especially in public spaces such as auditoriums, to keep the panels from shaking loose and raining down, during an earthquake, upon a gathering seated below.
Hold down clips are also used in suspended ceilings where pressure is exerted on the panels from below, such as in places where it is necessary to hose down the ceiling with water, for sanitary purposes. The clips keep the panels anchored in place.
The prior art generally uses hold down clips, of the type shown, for instance, in U.S. Pat. Nos. 4,027,454 and 4,858,408, to secure the panels in the above cited installations.
The clips are usually of metal and are either of the spring type as shown in the '408 patent, or of a panel piercing type, with tabs to secure the clip to the beam, as shown in the '454 patent.
These prior cut clips vary in complexity, effectiveness, and ease of installation.